MAINTAINERS: Add bits.h to the BITMAP API record

>From time to time changes are tending to go to the bits.h
headers while it may affect other bit operataions. Add
the bits.h to the BITMAP API record.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Yury Norov <yury.norov@gmail.com>
Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Yury Norov <yury.norov@gmail.com>

MAINTAINERS

@@ -3565,9 +3565,11 @@ R:	Andy Shevchenko <andriy.shevchenko@linux.intel.com>
 R:	Rasmus Villemoes <linux@rasmusvillemoes.dk>
 S:	Maintained
 F:	include/linux/bitmap.h
+F:	include/linux/bits.h
 F:	include/linux/cpumask.h
 F:	include/linux/find.h
 F:	include/linux/nodemask.h
+F:	include/vdso/bits.h
 F:	lib/bitmap.c
 F:	lib/cpumask.c
 F:	lib/cpumask_kunit.c
@@ -3575,7 +3577,9 @@ F:	lib/find_bit.c
 F:	lib/find_bit_benchmark.c
 F:	lib/test_bitmap.c
 F:	tools/include/linux/bitmap.h
+F:	tools/include/linux/bits.h
 F:	tools/include/linux/find.h
+F:	tools/include/vdso/bits.h
 F:	tools/lib/bitmap.c
 F:	tools/lib/find_bit.c